This invention relates to an apparatus for protecting the bottoms of liquid filled tanks in general and underground flammable liquid storage tanks in particular.
As has been set forth in the above-referenced application, graduated gauge sticks are commonly used to measure the quantity of a liquid in an underground tank by introducing the elongated gauge stick from ground level through the fill opening. To do so, typically, the gauge stick or rod is dropped through the fill opening into the tank until the stick touches bottom, whereupon it is removed for a determination of the height of the liquid within the tank by observing the wetted portion of the gauge stick.
The combined frequency generated by the application of gauge sticks and other objects such as sharp edges of suction pipes used with sludge water removal pumps to the bottom of the tank has resulted in punctures to the tank, especially in underground tanks which are fabricated of fiberglass. These punctures usually require the replacement of the entire tank, an expensive and time consuming operation. Where the puncture results in leaks of flammable or toxic liquids, serious safety hazards can be created.